Total heat energy recovery system for furnace-process phosphoric acid

Patent metadata

Field	Value
Publication number	US-12398039-B2
Application number	US-202217738710-A
Country	US
Kind code	B2
Filing date	May 6, 2022
Priority date	Mar 8, 2021
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A total heat energy recovery system for furnace-process phosphoric acid is disclosed by the present disclosure. The system comprises a phosphorus burning tower, a hydration tower, an absorption tower, a Venturi tube, a demister, an induced draft fan, a deaerator, an economizer, a dilute acid circulating tank, a phosphoric acid pump, and a feedwater pump. In consideration of the whole process system, fresh soft water is deoxidized after being heated by an upper head of the phosphorus burning tower and a gas guide tube, and the deoxidized water is then pumped into the economizer by a high-pressure pump to recover the heat of the hydration tower and then enters a steam pocket of the phosphorus burning tower to generate medium-high pressure steam. Therefore, unified recovery of the heat of a furnace-process phosphoric acid device is achieved, the medium-high pressure steam is generated, the effective energy is improved.

First claim

What is claimed is:

1. A total heat energy recovery system for furnace-process phosphoric acid, comprising a phosphorus burning tower ( 1 ), the lower part of the phosphorus burning tower ( 1 ) is provided with an air inlet through which yellow phosphorus and air enter the phosphorus burning tower ( 1 ); soft water enters the phosphorus burning tower ( 1 ) from an upper head at the top of the phosphorus burning tower ( 1 ), one end of a gas guide tube ( 1 - 1 ) is connected to the phosphorus burning tower ( 1 ), and the other end of the gas guide tube ( 1 - 1 ) communicates with the top of a hydration tower ( 2 ); after being heated by the gas guide tube ( 1 - 1 ), the soft water passes through a pipeline and is mixed with part of steam to be conveyed into a deaerator ( 7 ), and a water outlet of the deaerator ( 7 ) communicates with a soft water inlet of an economizer ( 8 ) through a feedwater pump ( 13 ); a gas outlet of the hydration tower ( 2 ) is connected to a gas inlet of an absorption tower ( 3 ), a polyphosphoric acid outlet of the hydration tower ( 2 ) is connected to a polyphosphoric acid inlet of the economizer ( 8 ) through a first phosphoric acid pump ( 10 ), a soft water outlet of the economizer ( 8 ) communicates with a steam pocket of the phosphorus burning tower through a pipeline, a steam outlet of the steam pocket of the phosphorus burning tower communicates with a steam inlet of a steam manifold, and the steam is discharged from a steam outlet of the steam manifold; a polyphosphoric acid outlet of the economizer ( 8 ) communicates with a polyphosphoric acid inlet of the hydration tower; a phosphoric acid outlet of the absorption tower ( 3 ) respectively communicates with a phosphoric acid inlet of the hydration tower ( 2 ) and a phosphoric acid inlet of the absorption tower ( 3 ) through a second phosphoric acid pump ( 11 ), and a gas outlet of the absorption tower ( 3 ) communicates with a gas inlet end of a Venturi tube ( 4 ); a gas outlet of the Venturi tube ( 4 ) communicates with a gas inlet of a demister ( 5 ), and a gas outlet of the demister ( 5 ) discharges end gas through an induced draft fan ( 6 ); a dilute phosphoric acid outlet of the Venturi tube ( 4 ) communicates with a liquid inlet of a dilute acid circulating tank ( 9 ), and a liquid outlet of the dilute acid circulating tank ( 9 ) communicates with a liquid inlet of the Venturi tube ( 4 ) through a third phosphoric acid pump ( 12 ); the soft water enters the upper head of the phosphorus burning tower ( 1 ) and the gas guide tube ( 1 - 1 ) to be heated, then enters the deaerator ( 7 ), is pumped into the economizer ( 8 ) by the feedwater pump ( 13 ) to recover sensible heat of gas and heat of hydration of phosphorus pentoxide which are brought into the hydration tower by the phosphorus burning tower gas, and then enters the steam pocket of the phosphorus burning tower ( 1 ) to serve as boiler feed water, thus generating steam with different pressure grades by recovering heat of reaction of yellow phosphorous of the phosphorus burning tower ( 1 ).

2. The total heat energy recovery system for furnace-process phosphoric acid according to claim 1 , wherein the economizer comprises a cylinder body ( 8 - 8 ) located in the middle, and a polyphosphoric acid inlet head ( 8 - 1 ) and a polyphosphoric acid outlet head ( 8 - 10 ) located at the two ends; the polyphosphoric acid inlet ( 8 - 3 ) is located at the polyphosphoric acid inlet head ( 8 - 1 ), the polyphosphoric acid outlet ( 8 - 12 ) is located at the polyphosphoric acid outlet head ( 8 - 10 ), the soft water outlet ( 8 - 4 ) is located at the cylinder body ( 8 - 8 ) close to the polyphosphoric acid inlet ( 8 - 3 ), and the soft water inlet ( 8 - 13 ) is located at the cylinder body ( 8 - 8 ) close to the polyphosphoric acid outlet ( 8 - 12 ); a polyphosphoric acid inlet thermocouple ( 8 - 2 ) is arranged on the polyphosphoric acid inlet ( 8 - 3 ), a polyphosphoric acid outlet thermocouple ( 8 - 11 ) is arranged on the polyphosphoric acid outlet ( 8 - 12 ), a soft water outlet thermocouple ( 8 - 5 ) is arranged on the soft water outlet ( 8 - 4 ), and a soft water inlet thermocouple ( 8 - 14 ) is arranged on the soft water inlet ( 8 - 13 ).

3. The total heat energy recovery system for furnace-process phosphoric acid according to claim 2 , wherein the heads are installed to the cylinder body ( 8 - 8 ) by flanges ( 8 - 9 ).

4. The total heat energy recovery system for furnace-process phosphoric acid according to claim 2 , wherein baffle plates ( 8 - 6 ) and heat exchange tubes ( 8 - 7 ) are arranged in the cylinder body ( 8 - 8 ), the baffle plates ( 8 - 6 ) are vertically arranged in a staggered mode, and the heat exchange tubes ( 8 - 7 ) are arranged in an axial direction of the cylinder body ( 8 - 8 ).

5. The total heat energy recovery system for furnace-process phosphoric acid according to claim 1 , wherein in the hydration tower ( 2 ), the polyphosphoric acid is used to absorb phosphorus pentoxide gas, the concentration of the polyphosphoric acid is controlled to be 105%-120% in terms of H 3 PO 4 , and the temperature of the polyphosphoric acid is 160-220° C.

6. The total heat energy recovery system for furnace-process phosphoric acid according to claim 1 , wherein the economizer ( 8 ) is a shell-and-tube heat exchanger and is made of nickel-chromium-molybdenum alloy steel or corrosion-resistant alloy steel.

7. The total heat energy recovery system for furnace-process phosphoric acid according to claim 1 , wherein the heat of the polyphosphoric acid entering the economizer ( 8 ) is absorbed by the soft water in the economizer ( 8 ).

Assignees

• Univ Kunming Science & Technology

Inventors

• Mei Yi
• Zhu Yuanzhi
• Nie Yunxiang
• Long Ping
• Xie Delong

Classifications

• F27D17/13

  using regenerative heat exchangers · CPC title

• C01B25/20

  Preparation from elemental phosphorus or phosphoric anhydride · CPC title

• F27D17/10

  Arrangements for using waste heat · CPC title

• F22D1/50

  incorporating thermal de-aeration of feed-water (de-aeration produced in the course of direct heat transfer F22D1/28) · CPC title

• F22D1/00

  Feed-water heaters, i.e. economisers or like preheaters · CPC title